Legal Question in Wills and Trusts in California

First off, the power of attorney is not legally relvant. The power of attorney expired immediately upon your husband's death. Powers of attorney only extend to what the grantor of the power could do themselves. Since a dead person cannot do any legal act, the POA dies with them. Any one can open the will and file it with the probate court along with a petition to be named executor of the will or administrator of the estate, which is where it gets a little tricky. The new, unsigned will, is not a valid will no matter what. The question is whether you have a revocation of the old will. Either the old will is still valid or it has been revoked and your Ex will be legally deemed to have died intestate (without a will). If the person filing the probate thinks (or wants) the old will to be valid, then they would file as the executor of the will. If they think or want the old will to be deemed revoked, they would file to be administrator of the intestate estate. And that pretty much hits the limit of what can be dealt with or explained in an internet Q&A. You'll need to sit down with an attorney, both wills, and any other related documents and correspondence to get any kind of reliable evaluation of the situation.